CODEWITHSUNDEEP
javaswingjframejpanel
user21902195
user21902195

Reputation: 85

Converting JFrame to JPanel

I currently have written some Java Swing using a JFrame and it works fine.

But now I need to use multiple screens and they are done using cardlayouts.

So i need to convert my JFrame to JPanel. Currently I have this line for my JFrame

mainFrame.getContentPane().add(c4Panel,BorderLayout.CENTER);

But if I convert mainFrame to JPanel I cant use getContentPane() IDE tells me to use getRootPane()

but I get error on this line

mainPanel.getRootPane().add(c4Panel,BorderLayout.CENTER);

The error I get is 

Exception in thread "main" java.lang.NullPointerException

Upvotes: 4

Views: 3492

Answers (1)

Andrew Thompson
Andrew Thompson

Reputation: 168825

mainPanel.getRootPane().add(c4Panel,BorderLayout.CENTER);

Should just be:

mainPanel.add(c4Panel,BorderLayout.CENTER);

The code:

mainFrame.getContentPane()

..is simply returning a container which itself has an add() method, and the getContentPane() part has been unnecessary for some time.

Upvotes: 3

Related Questions